1. Field of the Invention
The present invention relates to an alignment disk for use in adjusting the tracking and azimuth of a magnetic head of, for example, a floppy disk drive.
2. Description of the Related Art
A magnetic head of a floppy disk drive needs the proper tracking and azimuth adjustments with respect to a track on a recording medium. In a double-sided type floppy disk drive, the adjustments should be executed with respect to each magnetic head of sides 0 and 1. Without such adjustments, disk compatibility would be lost.
An alignment disk of a dibit pattern system is typically used for the tracking and azimuth adjustments. This alignment disk has adjustment data recorded thereon, which consists of dibit patterns of tracking patterns e to h and azimuth patterns I to L, as shown in FIG. 1. As shown in FIG. 2 , patterns e-h and I-L alternately recorded on predetermined track 11' of alignment disk 10. Such alignment disk 10 is set in a floppy disk drive having a magnetic head which is the object for the adjustments and is accessed there. The object magnetic head reproduces an output signal corresponding to the adjustment data from disk 10. Based on the voltage level of the reproduced output signal, the tracking and azimuth of the object magnetic head are adjusted.
As shown in FIG. 1, when magnetic head 12 is positioned on the track center TC of track 11', and when it has no azimuth shift between the center line GC of its gap 13 and a line orthogonal to the track center TC, output signals Ve to Vh are reproduced from tracking patterns e-h of alignment disk 10 and output signals V.sub.I to V.sub.L are reproduced from azimuth patterns I-L. These signals would have waveforms be as shown in FIG. 3A. In this case, since the center of the width of gap 13 coincides with track center TC, the individual signals Ve-Vh have the same voltage level. In addition, since there is no azimuth shift of center line GC of gap 13 of head 12, the individual signals V.sub.I -V.sub.L also have the same voltage level. If magnetic head 12 is shifted in the "+" direction with respect to track center TC, the output signals reproduced from tracking patterns e-h would have the voltage levels, Ve&gt;Vf and Vg&gt;Vh, as shown in FIG. 3 B. If magnetic head 12 is inclined in the " +" direction with respect to the orthogonal line to the track center TC, the output signals reproduced from azimuth patterns I-L would have the voltage levels, V.sub.I &gt;V.sub.J and V.sub.K &gt;V.sub.L, as shown also in FIG. 3B. FIGS. 3A and 3B actually illustrate the conceptual waveforms that represent changes in voltage level of these output signals. Based on such output signals reproduced from magnetic head 12, the tracking and azimuth of head 12 are adjusted.
With the use of the aforementioned alignment disk 10, however, it is necessary to alternately record, on a predetermined track, plural types of dibit patterns serving as the tracking and azimuth patterns. This complicates the process for recording the adjustment data on alignment disk 10 and requires a significant amount of time for the job.